Cylinder hone



H. R. BILLETER CYLINDER HONE Dec. 13, 1955 3 Sheets-Sheet 1 Filed July 3l 1951 Q@ N@ J. w

INVENTOR.

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Lim/N \NQNQQW SN @N www @MQW @vii www ccc United States; PafenfO CYLINDER HONE Henry Robert Billeter, Highland Park, lll., assigner' to Ammco Tools, Inc., North Chicago, Ill., a corporation of Illinois This invention relates generally to cylinder hones and has to do more particularly with an expansible hone adapted for honing small diameter cylinders such as brake cylinders, piston pin holes, bearing bushings and the like.

Expansible, small diameter hones have been constructed heretofore with a small number of abrasive, elements, namely, usually one or two and sometimes three. It has been found that hones having such a small'number of abrasive elements do not cut a truly round hole because of the tendency of the hone to cut the cylinder walls so as to form corners numbering one more than the number of abrasive elements in the hone. I n general, a more nearly round hole can be cut by employing a large number of abrasive elements and preferably at least four such elements should be used. Also, where the cylinder wall is provided with a recess such as an oil groove, there is a tendency for a hone having only a small number of abrasive elements to cut the cylinder eccentrically which tendency is lessened where a larger number of abrasive elements are used.

In prior small diameter expansible hones the so-called stone units consisting ofthe abrasive elements and the carriers to which the elements are attached are disposed in guide slots provided in a mounting body and expanding members for moving the stone units outwardly of the mounting body also are disposed in the respective slots along with the stone units. Because of this arrangement and the small space available in the mounting body and, in addition, the necessity of providing sufiicient material in the body for requisite strength and rigidity, it was not practicable to provide a larger number of abrasive elements than was used heretofore. f

An object of the present invention is to provide an expansible, small diameter hone which is capable of honing a cylinder to a high degree of accuracy.

Another object is to provide a small diameter hone of the type having a plurality of expansible abrasive elements which hone has great strength and rigidity and in which hone the abrasive elements have a relatively large range of expansion and are stably supported in all positions throughout such expansion range.

Another object is to provide an expansible hone having a new and improved arrangement for supporting the abrasive elements for expansion and contraction on the hone body.

A further object of the invention is the provision of an expansible hone of the character above referred to having novel and effective means for expanding the abrasive elements. v A further object is to provide a hone of the expansible type wherein-'the abrasive stone-carrier-units are directly supported on the hone body for radial expansive movement thereon and the body itself serves to effect such radial movement of the unit upon longitudinal movement of the latter in the body.

2,726,494 Patented Dec. 13, 1955 ICC Another-object is to provide a hone of the type having a body and stone-carrier-units expansible thereon in which hone the stone-carrier-units are supported against radial thrust solely by the body in all portions of expansion of the units in such a way that the entire force exerted on the units in the honing operation is transmitted directly from the body to the units.

Another object is to provide an expansible hone of the type having a slotted body and stone-carrier-units mounted on said body for expansion and contraction in which hone the stonecarrier-units are supported by means located externally of the slots and which also serves to effect radial, expansive movement of the units in the body upon longitudinal movement of such units.

Still another object of the invention is the provision of a hone having an integral body and a plurality of expandible and contractible stone-carrier-units mounted thereon having such a construction that in a honing operation the radially inward thrust of the units is transmitted directly to the integral body and the units are retained in expanded positions by actuating members arranged for resisting longitudinal thrust which forms one component of the force exerted by the units, with the result that no relatively movable parts or elements are relied on for receiving radially inward thrust of the units, and in which the actuating members yieldably urge the abrasive units radially inwardly.

A further object is the provision of a hone of the type including a body and stone-carrier-units carried thereby, wherein novel means are provided for effecting expansion of the units, which means detachably engage the units in such a way as to enable the units to be detached from the expanding means as an incident to removal of the units from the body.

Another object is lthe provision, in one form of the invention, of a hone of the type including a body and stone-carrier-units carried thereby, wherein novel means are provided for expanding the units and which engage the ends ofthe units solely by abutment, thereby eliminating the necessity for disconnecting the units from the expanding means.

Still a further object is the provision, in another form of the invention, of an expansible hone of the type having a body and a plurality of stone-carrier-units movable thereon for expansion and contraction and having shiftable actuator means for moving the stoneacarrier-units to effect expansive movement, which means also yieldably retains the units on the body and, in addition, upon appropriate shifting movement, serves to effect contraction of the units on the hone.

Another object is to provide in one of the forms of the invention, a hone of the type including a body and stonecarrier-units carried thereby, wherein novel means are provided for retaining the units in the body of simple and inexpensive construction, and having smooth action and long-wearing qualities.

Other objects ofthe invention are to provide a hone which is very simple and easy to manufacture; which has a very small number of parts; which is highly etiicient in operation; and which is strong and rugged and even when made in small sizes is suiciently rugged to resist breakage.

Other objects will appear from the following description taken in conjunction with the accompanying drawings, in which:

Figure l is a side elevational view of a hone embodying one form of the present invention;

Fig. 2 is an enlarged axial sectional View of the head end portion of the hone of Fig. l showing the hone in contracted condition;

Fig. 3 is a view similar to Fig. 2 but vshowing the hone in an expanded condition;

Fig. 4 is an elevational view of the head end portion of the hone, with one of the stone-carrierunits removed and showing the drive shank in section;

Fig. 5 is a sectional view taken on line 5 5 of Fig. 2;

Fig. 6 is a sectional view taken on line 6 6 of Fig. 2;

Fig. 7 is a sectional view taken on line 7-7 of Fig. 2;

Fig. 8 is a sectional view taken on line 8-8 of Fig. 3,

Fig. 9 is an end view taken on line 9-9 of Fig. 2;

Fig. l0 is an exploded view of one of the stone-carrierunits utilized in the hone of Figs. 1 to 9, with its actuating element;

Fig. l1 is a side view of the head end portion of a hone embodying another form of the invention, showing the head and a portion of the actuating means for the abrasive elements in elevation and the drive shank in section;

Fig. 12 is a longitudinal sectional view of the modified form of end portion of the hone of Fig. 1l;

Fig. 13 is an end view taken from the outer end of the hone of Fig. 11;

Fig. 14 is a sectional view taken along line 14-14 of Fig. 12;

Fig. 15 is a sectional view taken along line 15--15 of Fig. 12;

Fig. 16 is a sectional view taken along line 16-16 of Fig. 12;

Fig. 17 is a sectional view taken along line 17-17 of Fig. 12', and

Fig. 18 is a perspective view of one of the stone-carrierunits utilized in the hone of Figs. 1l to 17.

This application is a continuation-in-part of my application Serial No. 198,207, filed November 29, 1950, now abandoned.

The hone shown in Fig. 1 includes a drive adapter 12 forming means for directly mounting the hone on a honing machine (not shown) for rotatively driving the hone. The hone also includes a drive shank 14 fixed to the drive adapter and carrying a honing head 16 for rotation therewith. The honing head 16 of the present invention is of the expansible and contractible typevwherein a plurality of abrading elements 50 commonly known as stones are suitably mounted on a body 32 (Fig. 1) for expansion and contraction thereby to permit them to be urged into abrading engagement with the wall of the cylinder to be honed. Each stone 50 forms a portion of a stone-carrierunit or abrasive unit 51 (Fig. 10), hereinafter more fully described, which includes also a carrier 52 for mounting the stone on the body 32. A centering cone 1S is slidably and rotatably mounted on the drive shank 14 with its small end directed toward the honing head 16 for the usual purpose.

Referring now to the detail construction of the hone of Figs. 1 to 10, the drive shank 14, as seen especially in Figs. 2, 3 and 4, is tubular. One end is tapered as indicated at 20 (Fig. l) and inserted in a correspondingly shaped aperture in the drive adapter 12, with the end of the shank projecting into the cavity or hollow portion 24 of the drive adapter. The inner end of the drive shank (left-hand end as viewed in Fig. l) is threaded for receiving a nut 22, which secures the shank in the drive adapter. A push rod 26 is slidably mounted in the tubular drive shank 14 with one end extending beyond the end of the shank and into the cavity 24 for engagement by suitable means (not shown) for advancing the push rod and thereby expanding the stone-carrier-units 51. Advancement of the pushrod 26 causes expansion of the stone-carrier-units in the honing head 16 in a manner to be referred to later. The outer end of the drive shank 14 (right-hand end as viewed in Fig. l) is provided with a slightly enlarged counterbore 28 having interior threads 30 for receiving and mounting the honing head.

The honing head 16 constitutes an entirely novel device which includes a plurality (four) of stone-carrierunits 51 and for the purpose of mounting such number of units 51, which may be of relatively large size as compared with the diameter of the hone, a honing head body 32 of novel form is provided. The body 32 is formed as an integral, one-piece rigid member and includes an outer enlarged portion 34 generally cylindrical in outer contour but with cutout configurations and an inner, reduced, shank or stem portion 36 adapted to be inserted in the end of the tubular drive shank 14 and having threads 38 cooperable with the threads 30 for securing the honing head in the drive shank. Longitudinally extending, circumferentially spaced slots 40 are suitably formed in the body 32, as by milling. These slots 40 open out through the outer end of the body and extend through the reduced portion 36 and open out through the inner end of the latter portion and thereby open into the interior of the drive shank 14. The slots 40 extend radially inwardly to an appropriate depth leaving a central core 42 (Figs. 2 and 3). In order to provide the desired strength in the body of the honing head, the slots 40 are not cut square at their inner corners, but with diagonal surfaces 43 (Figs. 6 and 9) forming webs 45 of substantial dimensions and strength. Intermediate the ends of the enlarged portion 34 of the body 32, the slots are cut through the core as indicated at 44 forming a passage extending transversely or diametrically through the body 32 of the honing head and communicating with each of the slots 40. The cutout portion 44 enables the stone-carrier-units 51 to be contracted to a maximum extent. The stone-carrier-units 51 are mounted individually in the slots 40 and cooperate with the body 32 of the honing head in a novel manner such as to produce the results and advantages enumerated above.

The stone-carrier-units 51 will be described in detail later, but reference is first made to the camming surfaces 46 on the body of the honing head adapted to cooperate with the units for expanding them. The camming surfaces 46 extend longitudinally on each side of each slot being inclined with respect to the axis of the honing head and at positions spaced longitudinally of the head.

The camming surfaces 46 are arranged in pairs with respect to individual slots, each pair being formed by a notch 47 cut in the body transversely of, or across, the slot, the notch extending beyond the axial dimension of the respective camming surface, with the bottom surface of the notch running parallel with the axis of the head, forming connecting portions 48 extending axially from the bases of the caming surfaces to the adjacent cylindrical portion of the body. As mentioned, the notches are cut transversely, or across, the respective slots, whereby the camming surfaces are positioned externally of the slots, extending laterally therefrom on opposite sides. The depth of the slots and the notches relative to the diameter of the body 32 is such that the notches forming the camming surfaces intersect circumferentially around the body with the result that the several notches form continuous cut-out portions surrounding the body.

One of the stone-carrier-units 51 (hereinafter sometimes referred to as abrasive units) is shown in Fig. 10 and includes a carrier 52 of novel form and carrying on its upper surface a suitable abrasive element such as an abrasive stone 50 permanently secured thereto by appropriate means, such as by cementing the stone to the carrier.

The carrier 52 (Fig. 10) preferably includes a generally rectangular body having cam lugs 54 extending laterally outwardly from each side thereof and spaced longitudinally along the body at spacings corresponding to the longitudinal spacing of the camming surfaces 46. The cam lugs 54 are arranged to enter the corresponding two notches 47 when the stone-carrier-units are placed in the respective slots 40 and to bear against the surfaces of the notches 47 which extend from each side and longitudinally of the respective slots, namely the bottom surfaces 48 and the cam surfaces 46, and to ride up on the latter when the stone-carrier-units 51 are shifted longitudinally outwardly of the body 32 from their normal, retracted positions, as hereinafter explained more in detail. Each cam lug 54 includes a bottom at surface 56 and inclined end cam surfaces 58, the surfaces 58 being symmetrical; also the cam lugs 54 themselves are symmetrically arranged with respect to the carrier so that the stone-carrierunit can be indiscriminately turned end for end and used in either position in the honing head. Also all of the carriers 52 are identical so that they are fully interchangeable. The cam lugs 54 are of suiicient depth or thickness to provide the necessary strength and to insure against shearing olf at their junctures with the body of the carrier 52. At the same time they terminate sufficiently above the bottom of the body to permit the body to extend sufficiently into the slot to prevent the carrier from being displaced from the slot even when the units 51 are fully expanded, as hereinafter explained. Although it is desirable that the carriers 52 extend into the slots at all times, nevertheless it is not necessary that they do so to a great distance, and advantage is taken of this face in providing cam lugs of such size that they extend nearly to the bottom surface of the carrier, with resulting substantial dimension in that direction and corresponding strength.

Extending downwardly from the under surface of the carrier body 52 and longitudinally centrally thereof is a retaining lug 60, which lug 60 includes a longitudinally extending web portion 62 and a head portion 64, the latter having extensions 66 projecting laterally from the web 62. The upper surface of each extension 66 is provided with inclined surfaces 68 disposed transversely of the web 62, the two surfaces 68 on each side of the web 62 inclining longitudinally upwardly and inwardly toward each other forming a high point centrally thereof, and the radially innermost surface of each lug is tapered with a longitudinally extending apex. The lug 60 is also symmetrical in such manner as to be effective regardless of the end-to-end position of the stone-carrier-unit in the honing head.

When the honing head is to be assembled, the stone units or abrasive units 51 arev inserted in the slots 40 with lthe cam lugs 54 extending itno the notches 47, and when the units are in their innermost, contracted position, the cam lugs engage the connecting portions 48 and the outer surfaces of the stones 50 extend only slightly beyond the outer surface of the body 32. Upon outward longitudinal sliding movement of the units (to the right as viewed in Figs. l to 4) the cam lugs S4 ride upon the camming surfaces 46 from the contracted position of Fig. 2 to the expanded position of Fig. 3.

In accordance with my invention means are provided for moving the abrasive units 51 longitudinally in the body 32 to thereby expand or contract the units, which means also serve to retain the stone units in the body and to resiliently urge them toward retracted position. To this end an actuating element 70 (Fig. 10) is provided for each abrasive unit 51 which element includes an elongated flat body portion 72 having an inturned latch portion 74 at one end. At the other end the actuating element is forked having a slot 76 and a pair of fingers 78, the latter being bent out of the plane of the body portion 72 with their ends curved slightly toward the plane. The actuating element 70 is of spring material, and it is capable of flexing transversely of its long dimension but in the use of the device in the hone it is operable for transmitting thrust longitudinally substantially without exing, The elements 70 are disposed in the slots 40 with the forked fingers 78 straddling the web 62 of the respective carriers 52 and the opposite ends extending through the slots 40 into the interior of the drive shank 14 where their innermost ends are fitted in corresponding notches vor slots in a spring guide or keeper 80. The spring guide 80, shown also in Fig. 5, takes the form of a generally vcylindrical element having substantial axial dimension and a central aperture receiving an extension 82 on the adjacent end of the push rod 26. The spring guide 80 abuts a shoulder 84 on the push rod 26 for limiting. movement of the spring guide on the push rod thus forming a space in which the latch portions 74 extend. Upon movement of the push rod 14 outwardly (to the right as viewed in Figs. 1 to 4) it engages the latch portions '74 and moves the actuating elements 70 in a corresponding direction to thereby expand the abrasive units 51. A compression spring 86 is interposed between the spring guide and the adjacent end of the honing head body in surrounding relation to the extension 82 and a projection 83 on the honing head body. Upon movement of the push rod 26 in expanding direction, its movement is limited by engagement of the extension 82 and projection 88. Upon release of the moving force, the spring 86 moves the push rod and consequently the actuating elements 70 in contracting direction.

The forked fingers '78 of each actuating element 70 in position straddling the web 62 of the corresponding abrasive unit Si are normally urged into engagement with the adjacent inclined surface 68, as shown in Figs. 2 and 3. Upon movement of the actuating elements 70 in expanding direction (to the right as viewed in the drawings) there is positive force transmitted to the abrasive units 51 by the base of the slot 76 directly engaging the web 62. Such movement moves the abrasive units to expanded position, as shown in Fig. 3, and during such movement the outer ends of the actuating elements 70 flex outwardly to a minor extent but not suicient to impair the longitudinal thrust imparted to the abrasive units.

Upon release of the force moving the actuating elements outwardly in expanding direction (to the right in Fig. 2), the spring 86 forces the actuating elements in contracting direction and due to friction engagement between the forked fingers 78 and the corresponding inclined surfaces 63, the abrasive units are drawn inwardly (to the left as viewed in the drawings) and the normal radially inward urge of the actuating elements carries the abrasive units radially inwardly to complete the contractin g operation.

Because of the cutout portion or passage 44 the lugs 60 are enabled to move radially inwardly until they inter engage as shown in Fig. 7 and because of this feature the stone units can be contracted to a maximum extent, since their inward movement is not limited by elements of the body. The inner tapered surfaces 0f the lugs 60 enable the lugs to extend inwardly toward the axis and toward each other to a maximum degree, while at the same time providing maximum mass and strength to the lugs.

The stone units may be readily inserted and removed from the honing head. For removing or ejecting a stone unit, the user merely applies pressure to the inner end (left end as viewed in Fig. 2) of the corresponding stone 50, as by pressing thereon with his thumb, in a direction to urge the unit toward the outer end of the body 32. As pressure is applied to the unit in such outward direction, the cam lugs 54 ride up on the camming surfaces 46 and the actuating elements 70 ex to permit the lugs 60 to ride out of the slots 76 and the unit to separate from the body. v

To permit insertion of the units in the body, the actuating elements must be in their retracted position (to the left as viewed in the drawings). If the actuating elements are not in such position they may conveniently be moved to such position by placing one-of the abrasive units in a position wherein the head portion 64 of the lug 60 engages the ends of the fingers 78, and then by forcing the unit into the slot it rides down the camming surfaces 46 and thereby moves longitudinally and forces all of the actutaing elements 70 in contracting direction (to the left, Fig. 2). The actuating elements are thus moved to a position beyond normal contracted position, whereby the remaining abrasive units can be readily inserted in the slots without hindrance from the actuating elements. Thereafter the push rod 26 is forced in expanding direction (to the right, Fig. 2) which forces the forked fingers 78 into position straddling the webs 62 and gripping the respective surfaces 68 of the lugs 60. Further movement of the push rod 26 and actuating fingers in expanding direction forces the stones to expanded position. In the honing operation, the head of the hone, with the abrasive units in place and retracted, is inserted in the cylinder to be honed. The hone is rotated in the usual manner and the abrasive units are expanded into contact with the cylinder wall by suitable actuation of the push rod advancing means (not shown). In the honing operation of the device all rotational thrust is imparted from the body 32 directly to the abrasive units through engagement between the lugs 54 and the surfaces on the body which cooperate therewith and there is no intermediate element for transmitting such thrust. The cam lugs 54 extending laterally outwardly from both sides of the abrasive units furnish four points of support for each unit on the honing head body. As a consequence it is not necessary to provide close fit between the stones and the walls of the slots. The cam lugs afford ample support for the units such that the latter do not move out of line or rock in the slots in the operation of the hone and they are completely stable under all normal conditions of use.

It is to be noted further that when the abrasive units are in fully expanded position, there is only a small portion thereof extending into the slots. In such position, their support is provided solely by the cam lugs resting on the camming surfaces, thus pointing to the fact that the walls of the slots as such are not relied on for support of the abrasive units, except to receive circumferential thrust of the units. For this reason, maximum expansion of the units is attained, while at the same time they are firmly supported in all positions in their range of expansion.

The thrust received from the abrasive units as a result of a honing operation is directed radially inwardly, which is transmitted to the body 32 in the same direction. This thrust is absorbed by the unitary, one-piece honing head body and for that reason stability of the abrasive units is assured. The camming action between the camming surfaces 46 and cam lugs 54 produces a longitudinal component of force which is resisted by the actuating elements 70 which in resisting that force retain the units in their adjusted expanded position. The longitudinal component of that force is easily resisted by the actu ating elements and the lateral or radial flexing of the fingers is limited by the small dimension of the slots 40 in that direction.

It will be seen that in the embodiment of the invention above described a single instrumentality is utilized for moving the stone units both to expanded and contracted positions. This instrumentality includes the actuating elements 70 and the means for moving them. It is here pointed out for the purpose of emphasis that the actuating elements 70 cause the abrasive units to be expanded by direct thrust, and to be contracted by the friction gripping of the forked fingers 7S with the inclined surfaces 68 and the spring action of the actuating elements normally urging the stone units radially inwardly. No means separate from the actuating elements is required for retracting the stones such, for example, as garter springs used in certain types of hones.

It is desired to point out a further advantage resulting from the novel construction of the hone of the present invention. As pointed out above, the retaining lugs 60 of the abrasive units are located longitudinally intermediate the cam lugs 54, and the actuating elements 70 urge the abrasive elements radially inwardly. As a result, all of the cam lugs 54 are retained in engagement with the respective camming surfaces 46. No means is provided outwardly of the cam lugs 54 for retaining the abrasive units in the slots, the units being retained solely by the actuating elements. In order to most effectively accomplish this action, the retaining lugs 60 are positioned on the inner surfaces of the abrasive units for most effective engagement by the actuating elements. The lugs 60 are accommodated by the transverse passage 44 into which the lugs extend, thus permitting the full` depth of the slots to be availed of for contracting the abrasive units. The abrasive units can therefore be rcontracted a maximum extent, and it is not necessary to employ separate means for contracting the abrasive units, such as garter springs as above mentioned, or outer camming surfaces for positively camming the units in contracted positions.

Because of the fact that the body 32 of the honing head is a solid integral article, the device is given great strength for its size and therefore vibration or chattering of parts making up the body is eliminated.

The hone of Figs. 1-10 and the hone of Figs. 11-18 have certain features in common, including those features whereby a number of abrasive units is employed in a honing head having relatively small dimensions; great stability of the abrasive units is assured; andthe abrasive units are readily detachable from the actuating elements enabling the abrasive units to be easily removed from the head and replaced therein.

The hone of Figs. 11-l8 includes a tubular drive shank similar to the drive shank 14 and its inner or connecting end (not shown) is mounted in a drive adapted (not shown) such as the drive adapter 12 referred to above. A bore 102 extends the greater part of the length 0f the drive shank, and terminates in an enlarged counterbore 104 at the outer end for receiving a connecting portion of the honing head. For the purpose of expanding the abrasive units in the hone, a push rod 106 is slidably mounted in the drive shank 100 and has its inner end extending into the drive adapter (not shown) for engagement by suitable means (not shown) for advancing the push rod 106 and thereby expanding the abrasive units, in a manner described in connection with the form of hone previously described. The outer end of push rod 106 is formed with a bore 108 for receiving the inner end of a stop pin 110 in a manner and for a purpose to be referred to later in detail.

The honing head 112 is generally similar to the honing head 16 in that the two heads are provided with similar arrangements of slots and camming surfaces for receiving and effecting expansion of the abrasive units. The hon ing head 112 as in the case of the first embodiment includes an integral body 113 having an enlarged portion 114 generally cylindrical in outer contour but with cutout configurations, and an inner reduced shank portion 116 adapted to be inserted in the counterborc 104 in the cuter end of the drive shank 100, having threads 118 cooperable with threads 120 in the counterbore for sccuring the honing head in the drive shank 100.

The integral body 113 of the honing head is provided with a plurality of slots 122 for receiving the abrasive units, and the elements for effecting expansion of the units. The slots 122 may be formed as by a milling operation and are circumferentially spaced around the head, extending longitudinally thereof and opening out through the outer end of the body as well as continuing through the reduced shank portion 116 of the head. The slots at their inner or bottom surfaces are not cut square but are provided with beveled corners 124, forming webs 125 extending radially outwardly from the core portion 126 of the head, adding to the strength of the head as between the core 126 and the outer portions of the body defining the side walls of the slots. The core portion is uniform in cross-sectional dimension throughout the length of the honing head including the shank portion 115.

For the purpose of aiding in expansion of the abrasive units, the honing head is provided with camming surfaces 128 similar in construction and arrangement to the camming surfaces 46 described above, being arranged in pairs respective to individual slots, each pair being formed by a notch 130 cutting the body transversely of, or across, the slot, the notch extending longitudinally beyond the axial dimension of the respective camming surfaces, with the bottom surface of the notch running parallel with the axis of the head forming connecting portions 132 extending axially from the bases of the camming surfaces to the adjacent enlarged portion of the body. As in the previously described embodiment the camming surfaces are positioned externally of the slots, extending laterally from opposite sides thereof. The depth of the slots and the notches relative to the diameter of the body is such that the notches forming the camming surfaces intersect circumferentially around the body with the result that the several notches form continuous cutout portions surrounding the body. The camming surfaces 128 lie in planes inclined to the slot bottoms respectively, and extending perpendicularly to radial planes bisecting the respective slots. The innermost notches 130 (to the left as viewed in Figs. l1 and 12) are spaced from the inner end of the head so as to leave an abutment surface 134 for engagement with the outer end of the drive shank 100.

The stone-carrier-units or abrasive units 136 are mounted in the slots 122 for longitudinal sliding movement and radial expanding movement, having cams 146 for coacting with the camming surfaces 128 for expanding the units in response to longitudinal sliding movement thereof. Each unit (Figs. 12 and 18) includes a body 138 of cross-sectional contour such as to conform generally to the cross-sectional contour of each slot. The radially outward surface 140 of the body 138 supports an abrasive stone 142 generally similar to the stone 50 and secured thereon in a similar manner. The stone 142 is of a shorter length than the body 138, the body having transverse grooves 144 for receiving retainer rings, as will be referred to later, for contracting the units in the honing head. As will be noted, the notches 144 are located longitudinally outwardly of the stone 142 and preferably are closely adjacent the ends of the stone. The notches 144 are preferably arcuate in a direction transversely of the body 13S so as to define generally circular notches for receiving the bands or rings 152 to be referred to later.

The abrasive unit body 138 is provided with cam lugs 146 extending laterally outwardly from each side thereof and spaced longitudinally along the body at a spacing corresponding to the longitudinal spacing of the camming surfaces 128. The cam lugs 146 are arranged to enter into the corresponding two notches 130 when the units are placed in the respective slots 122 and to bear against the Vsurfaces of the notches which extend from each side and longitudinally of the respective slots, namely the bottom surfaces 132 and camming surfaces 128, and to ride up on the latter when the units are shifted longitudinally outwardly of the body from their retracted positions as hereinafter explained more in detail. Each cam lug 146 includes a bottom at surface 148 and an inclined end cam surface 150. The abrasive unit 136 is inserted in its slot 122 in such position that the cam surfaces 150 are directed longitudinally outwardly of the honing head, i. e., adjacent the respective camming surface 128, the surfaces 150 being inclined complementally to the inclination of the camming surfaces 128 relative to the longitudinal axis of the hone. The dimensions of the lugs 146 relative to the abrasive unit body 138 are similar to those described above in connection with the cam lugs 54 with respect to strength and placement on the unit body and the relation between the units and the slots.

For the purpose of retaining the abrasive units in the slots and retracting the units when the expansive forces are released, l provide novel means in the form of yieldable bands or rings 152, encircling and engaging the several abrasive units, which rings are preferably formed of a synthetic elastomer, or so-called synthetic rubber having suitable properties such as strength, elasticity and durability. Neoprene has been found capable of accomplishing excellent results for the purposes intended, the material furthermore being highly resistant to oils and greases, grit, and other foreign matter. Such rings 152 are provided one at each end of the honing head and are positioned in the aligned notches 144 in the several abrasive units at each end of the honing head. The rings 152 yield sufiiciently to permit expanding movement or" the units, and are elastic so that, upon release of the expanding forces, they contract the units radially inwardly. The rings have sufcient stretch so that they can be expanded sufciently for passing them over the outer dimension of the body 112 such as is necessary in inserting the innermost ring. Preferably of course the units should be in retracted position when placing the rings in place.

Novel means are provided for expanding the abrasive units so as to enable removal and insertion of the units with facility. The expanding means loosely engages the units so that no manipulation of the former is required for removing the units from the head. The expanding means includes a plurality of pusher fingers 154, one being provided for each of the units and disposed in the corresponding slot 122. The outer ends of the fingers 154 have outturned portions 156 directly engaging the adjacent (inner) ends of the units 136 although detached therefrom. The inner ends of the pusher fingers 154 extend inwardly beyond the inner end of the shank portion 116 of the body and into the counterbore 104 and are provided at their inner ends with elongated slots in which are fitted complementally shaped projections 158 extending radially outwardly from a pusher head 160. The pusher head 160 has a central bore by means of which it is fitted on the stop pin 110, the stop pin extending into the counterbore 104 where the pusher head is located. The pusher fingers 154 are secured in position with respect to the projections v15S by any suitable means such as by staking the projections and fingers. The pusher head 160 is limited in movement forwardly with respect to the stop pin by means of a split ring or collar 162 fitted in a circumferential slot 164 in the stop pin. A return spring 166 is compressed between the split ring 162 and the inner end of the honing head, the latter forming a longitudinally fixed element of the hone. The compression spring 166 therefore urges the split ring 162, and thereby the stop pin 110, inwardly of the drive shank.

An overload compression spring 168, of substantially greater strength than the return spring 166, is compressed in preloaded condition between the pusher head and the outer end of the push rod 106 in surrounding relation to the stop pin 110. A lost motion connection is provided between the push rod 106 and the stop pin 110 for enabling the overload spring 168 to give way under the inuence of expanding pressure greater than a predetermined amount. The lost motion connection includes a slot 170 formed in the stop pin 110 and a key 172 in the push rod 106. The key 172 preferably takes the form of a portion of a circular disc (Fig. 14), being fitted in a slot cut transversely in the push rod 106 and extending into the slot 170 in the stop pin.

Under normal conditions the overload spring 16S urges the pusher head 160 and the stop pin 110 to the right (Fig. 12) relative to the push rod 106 whereby the key 172 abuts against the inner end of the slot 170. Upon advancement of the push rod 106 outwardly in the operation of expanding the abrasive elements, the spring 168 is suiiicient to retain the pusher head 160 and the stop pin 110 in the relative position just referred to with respect to the push rod 106, so that the pusher head 160 moves forwardly with the push rod without relative movement between the two. The overload spring and lost motion connection arrangement is disclosed and claimed in my copending application Serial No. 79,394, filed March 3, 1949, issued as Patent No. 2,637,954, May 12, 1953.

Upon advancing movement of the pusher head 160 by the push rod 106 as above described, the pusher head moves the pusher fingers 154 longitudinally outwardly and the fingers thereby slide the abrasive units longitudinally outwardly, camming them radially outwardly through thc coaction between the cam lags E45 and camming surfaces lZS. The strength of the overload spring 16S is sutlicient to compress the return spring 5.66 without compression of the overload spring, the return spring 166 being compressed until the outer end of the stop pin 110 engages the inner end of the honing head, limiting the movement of the stop pin, and any additional movement imparted to the push rod 66 thereafter compresses the overload spring 168 while the key 172 slides in the slot 170. Thus, when the forward movement of the stop pin is checked, an additional slight forward movement of the push rod 106, is permitted until the key 172 engages the forward or outer end of the sic-t 57S. Upon release of the expanding pressure applied to the push rod 166 the overload spring E63 moves the push rod rearwardly relative to the stop pin liti until the kcy 172 engages the inner end ofthe siot 17S if it is not already in engagement therewith. ri'hereafter the return spring 165 moves the stop pin lid and the pusher fingers 154 inwardly of the drive shank and, acting through the overload spring S, moves the push rod 366 inwardly of the drive shank as Well. When the abrasive elements 136 are limited in their radial expansive movement such as in engaging a cylindrical surface to be honed, and force is applied to the push rod i166 to an extent greater than that necessary for expanding the stone to the extent desired, the lost motion connection between the key 172 and slot 176 permits relative movement between the push rod and the stop pin lid, with the overioad spring teil giving way, without damage to any portion of the tool or the work-piece being honed.

The hone illustrated in Figs. ll-l8 possesses all of the advantages of the hone of Figs. l-lO with respect to facility of mounting the abrasive units in the honing head. The cam lugs Lid furnish four points of support for each abrasive unit on the honing head body. Maximum expansion of the units is attained; the units are expansible to positions wherein their radially inner surfaces are disposed radially outwardly of the inner surface of the drive shank. The fact that the pusher fingers are disconnected from the units facilitates maximum expansion of the units. The radial inward thrust of the abrasive units resulting from a honing operation is transmitted to the body, and is absorbed by the unitary onepiece body of the honing head. The longitudinal component of reaction force resulting from the camming action between camming surfaces 128 and cam lugs 146 is easily resisted longitudinally by the pusher fingers 154, this component of the force being absorbed by the pusher fingers with substantially no radial deflection or exing of the pusher fingers. There is no positive connection between the abrasive units and the pusher fingers and for that reason the abrasive units can be easily removed from and inserted in the honing head. The carrier retainer rings 152 are sufficiently yieldable to permit the desired expansion of the carrier units and sufficiently elastic to contract the units upon release of the expanding force. These rings also withstand deleterious effects of foreign material.

l claim:

l. A rotatable hone comprising a tubular drive shank, an integral body of greater diameter than the inner diameter of said drive shank and having a stem detachably secured thereto, said shank constituting means for supporting the body and having means adapted for connection with supporting and driving means, said body having longitudinal slots therein extending into the interior of said drive shank, and abrasive units mounted inA said slots for longitudinal and radial sliding movement therein, each having a main body portion with an outer abrasive face, said body and units having interengaging cam elements effective for moving the units radially outwardly in respouse to movement thereof longitudinally in one direction, said cam elements being positioned whereby said units are moved thereby to positions wherein their main body portions are disposed radially outwardly of the inner surface of said drive shank, actuating elements longitudinally slidable in said slots, the inner ends of said actuating elements extending into said drive shank and the outer ends thereof having operative engagement with said units for moving the units longitudinally in one direction, and a push rod longitudinally slidable in said drive shank and connected at one end to said actuating elements for moving the latter in said one direction and having its other end extended to a position adjacent the supported end of the shank for engagement by operating means.

2. A rotatable hone comprising an integral body having longitudinally disposed slots and longitudinally spaced camming surfaces extending laterally from opposite sides of each slot, and abrasive units disposed in said slots rcspectively for longitudinal and radial sliding movement therein and having laterally extending cam elements engageable respectively with said camming surfaces and effective therewith for moving the units radially outwardly in response to movement thereof longitudinally in one direction, said camming surfaces being wholly open-faced in radially outward directions whereby separation of the units therefrom in a radial direction is permitted, and actuating elements disposed in said slots respectively, for movement longitudinally therein and detachably engaging said units for moving the units in said one longitudinal direction.

3. A rotatable hone comprising in combination, a tubular drive shank, an integral body carried by the drive shank and having longitudinal slots therein and notches in its periphery transversely of the slots forming longitudinally spaced camming surfaces extending laterally from both sides of each slot, an abrasive unit disposed in each slot for longitudinal sliding movement therein and having laterally extending cam elements engageable with the respective camming surfaces and effective therewith for moving the units radially outwardly in response to longitudinal movement of the units in one direction, actuating elements disposed in said slots for longitudinal sliding movement therein and having detachable engagement with said units for moving the units longitudinally in said one direction, and operating means disposed in said drive shank for sliding movement therein and connected to said actuating elements for moving the latter longitudinally in said one direction.

4. A rotatable hone comprising a generally cylindrical body having a plurality of circumferentially spaced slots extending longitudinally thereof and radially inwardly from the periphery, a plurality of abrasive units guided in said slots respectively, and contractible therein to positions in which only a relatively small portion of each unit extends radially out of the respective slot and cam surfaces on said body wholly open-faced in radially outward directions and cam surfaces on said units engageable therewith disposed laterally outwardly of both sides of said slots and effective upon longitudinal displacement of said units in one direction in said slots for moving said units radially outwardly of said body, and means for moving said units longitudinally of said body to thereby effect radial movement of said units relatively to said body.

5. A rotatable hone comprising an integral body having longitudinally disposed slots formed therein and a transverse passage communicating with said slots, abrasive units guided in said slots for longitudinal and radial sliding movement and having portions extending into said passage to positions wherein their inner surfaces are adjacent the axis of the body when the units are positioned radially inwardly, said body having camming surfaces formed thereon adjacent and externally of the walls defining said slots, said units having cam elements en- 13 gageable with said camming surfaces and effective therewith, upon longitudinal movement of said units in one direction, for causing said unitsv to expand radially, and actuating elements in said slots respectively engaging said portions of said units for moving the units in said one direction.

6. A rotatable hone comprising an integral body having longitudinally disposed slots, abrasive units guided in said slots for radial and longitudinal sliding movement therein, said body having camming surfaces on opposite sides and externally of each slot but adjacent the walls thereof, and extending radially outwardly of the bottom surfaces of the slots, said units having laterally extending cam lugs engageable with said camming surfaces and effective therewith for expanding said units radially outwardly upon movement of the units longitudinally in one direction, the portions of said body forming said camming surfaces constituting the sole means for sustaining radial inward thrust of said units, and common means for moving said units longitudinally in expanding direction and for receiving the longitudinal thrust from said units due to radial inward thrust thereof and camming action of said camming surfaces and cam elements.

7. A rotatable hone comprising an integral body, abrasive units mounted on said body for rotation therewith and for longitudinal and radial sliding movement thereon, said units having uniform outer surfaces for engagement with a surface to be honed, said units and body having interengaging cam elements, respectively, eifective for moving said units radially outwardly upon movement thereof longitudinally in one direction, and actuating means carried by said body for movement longitudinally thereof, said actuating means including longitudinally extending, laterally resilient members connected to said units at the radially inner portions thereof and operable to impart nonyieldable thrust to said units longitudinally in said one direction and being yieldable radially outwardly and operative to urge said units radially inwardly, said resilient members being the sole means foropposing radially outward movement of said units.

8. A rotatable hone comprising an integral body having longitudinally disposed slots and longitudinally spaced camming surfaces on opposite sides of each slot, and abrasive units mounted in said slots respectively for longitudinal and radial sliding movement therein and having cam elements engageable respectively with said camming surfaces and effective therewith for moving the units radially outwardly in response to movement thereof longitudinally in one direction, said camming surfaces being wholly open-faced in radially outward directions whereby separation of the units therefrom in a radial direction is permitted, lugs extending radially inwardly from the inner surfaces of said units longitudinally intermediate the cam elements thereon, and actuating elements disposed in said slots respectively for longitudinal movement therein and detachably connected with respective lugs for moving the units longitudinally, said actuating elements being yieldable radially outwardly and effective for urging said units radially inwardly.

9. A rotatable hone comprising an integral body having longitudinally disposed slots, abrasive units disposed in said slots for radial and longitudinal sliding movement therein, said units being contractible in the slots to positions in which only a small portion of each unit extends radially out of the respective slot, said body having camming surfaces adjacent said slots, said camming surfaces being wholly open-faced in radially outward directions, said units having cam elements engageable with said camming surfaces and effective therewith for expanding said units radially outwardly upon movement of said units longitudinally in one direction, actuating elements l disposed in said slots for longitudinal sliding movement therein and having operable connection with respective units at the radially inner portions of the units, said actuating elements being non-yieldable longitudinally and 1.4 yieldable radially and operative for imparting nonyieldable longitudinal thrust to said units and for urging said units radially inwardly, and means for moving said actuating elements longitudinally in said one direction.

10. A rotatable hone comprising an integral body having longitudinally disposed slots, abrasive units disposed in said slots for radial and longitudinal sliding movement therein, said body having camming surfaces adjacent said slots, said units having cam elements engageable with said camming surfaces and effective therewith for expanding said units radially outwardly upon'movement of the units longitudinally in one direction, actuating elements disposed in said slots for longitudinal sliding movement therein, said actuating elements having positive connection with said units for moving the units longitudinally in expanding direction and friction connection therewith releasable in response to relative longitudinal movement in the opposite direction for moving the units longitudinally in said opposite direction, and means for longitudinally moving said actuating elements.

1l. A rotatable hone comprising in combination, an integral body having longitudinally disposed slots, abrasive units disposed in said slots for radial andlongitudinal Asliding movement therein, said body and units having respectively interengageable cam elements effective for expanding said units radially outwardly upon movement of the units longitudinally in one direction, said units having radially inwardly extending lugs each having a radial web and inclined surfaces disposed transverse thereto, actuating elements disposed in said slots for longitudinal sliding movement therein and having forked ends straddling said webs and bent radially inwardly to engage said inclined surfaces, said actuating elements being operative to move said units longitudinally in both directions and being radially yieldable and normally urging said units radially inwardly, and means for moving said actuating elements longitudinally.

12. A rotatable hone comprising a tubular drive shank, an integral body of greater diameter than the inner diameter of said drive shank and secured thereto, and having longitudinal slots therein communicating with the interior of said drive shank, and abrasive units mounted in said slots for longitudinal and radial sliding movement therein, said body and units having interengaging cam elements effective for moving the units radially outwardly in response to movement thereof longitudinally in one direction, said units being movable to positions wherein their radially inner surfaces are disposedlradially outwardly of the inner surface of said drive shank and having radially inwardly extending lugs, actuating elements disposed in said slots for longitudinal sliding movement therein, the inner ends of said actuating elements extending into said drive shank and the outer ends thereof having operative engagement with said lugs, said actuating elements being operative for moving said units disposed in both directions, and a push rod longitudinally in said drive shank for longitudinal sliding movement therein and connected to said actuating elements for moving the latter in said one direction.

13. A rotatable hone comprising in combination,'a tubular drive shank, an integral body including a reduced portion mounted in an end of said drive shank and an enlarged outer portion, said body having longitudinal slots therein communicating with the interior of said drive shank, abrasive units mounted in said slots for longitudinal and radial sliding movement therein, said body and units having interengaging elements effective for moving the units radially outwardly in response to movement thereof in longitudinally outward direction, said body having a transverse passage communicating with said slots, said units having lugs extending into said passage to positions wherein their inner surfaces are adjacent the axis of the body when the units are positioned radially inwardly, actuating elements disposed in said slots for longitudinal sliding movement therein and having their outer ends in operative engagement with said lugs and their inner ends extending into said drive shank, and operating means slidable in said drive shankand connected to said actuating elements for moving the latter longitudinally.

14. A rotatable hone comprising a generally cylindrical body having a plurality of circumferentially spaced slots extending longitudinally thereof and radially inwardly from the periphery, and recesses formed in the periphery of said body laterally beyond the sides of said slots and defining inclined cam surfaces, a plurality of abrasive units guided in said slots respectively and having projections extending laterally beyond said slots and into said recesses respectively and having inclined cam surfaces riding on said first-named cam surfaces whereby the latter are effective upon longitudinal displacement of said units in one direction in said slots to move said units radially outwardly of said body, and means including actuating elements disposed in said slots for sliding movement therein and engaging said units respectively for moving said units longitudinally of said body and for resiliently urging said units inwardly of said body to retain said first and second named cam surfaces in engagement.

l5. A rotatable hone comprising a generally cylindrical body having a plurality of circumferentially spaced slots extending longitudinally thereof and radially inwardly from the periphery, and a plurality of notches extending transversely across said slots respectively and providing outwardly of and adjacent the side walls respectively of cach slot cam surfaces inclined to the longitudinal axis of said body, a plurality of abrasive units guided in said slots respectively and having laterally extending projections disposed in said notches respectively and having inclined cam surfaces riding on said firstnamed cani surfaces whereby the latter are effective upon displacement of said units longitudinally of said body in one direction in said slots to move said units radially outwardly of said body, and means including actuating elements disposed in said slots for sliding movement therein and engaging said units respectively for moving said units longitudinally of said body and for resiliently urging said units inwardly of said body to retain said first and second named cam surfaces in engagement.

16. A rotatable hone comprising an integral body having longitudinal slots therein and a continuous core portion extending the length of the body, and having notches in its periphery transversely of the slots forming longitudinally spaced camming surfaces extending laterally from both sides of each slot, an abrasive unit disposed in each slot for longitudinal sliding movement therein and having laterally extending cam elements engageable with the respective camming surfaces and effective therewith for moving the units radially outwardly in response to longitudinal movement of the units, said units having radially inner surfaces substantially uniform in cross section substantially throughout the length of the units, actuating elements disposed in said slots for longitudinal sliding movement therein engageable with the adjacent end surfaces of said units solely by abutment therewith for moving the units longitudinally, and means yieldingly urging said units radially inwardly.

17. A rotatable hone comprising an integral body having longitudinally disposed slots and longitudinally spaced camming surfaces extending laterally from opposite sides of each slot on the outer surface of the body, abrasive units disposed in said slots respectively for longitudinal and radial sliding movement therein, said abrasive units being no greater in width than the slots and having laterally extending cam elements engageable with said camming surfaces and effective therewith for moving the units radially outwardly in response to movement thereof longitudinally in one direction, and actuating elements disposed in said slots respectively for movement longitudinally therein and detachably engaging said units for moving the units in said one longitudinal direction.

18. A rotatable hone comprising an integral body having longitudinally disposed slots and longitudinally spaced camming surfaces extending laterally from opposite sides of each slot, and abrasive units disposed in said slots respectively for longitudinal and radial sliding movement therein and having laterally extending cam elements engageable respectively with said camming surfaces and effective therewith for moving the units radially outwardly in response to movement thereof longitudinally in one direction, said camming surfaces being wholly open-faced in radially outward directions whereby separation of the units therefrom in a radial direction is permitted, and actuating elements disposed in said slots respectively for movement longitudinally therein and engaging the adjacent end surfaces of said abrasive elements solely by abutment therewith for moving the abrasive eiements in said one longitudinal direction.

19. A rotatable hone comprising a tubular drive shank, a generally cylindrical body mounted on the shank, a plurality of abrasive elements movably carried by said body, mutually interengageable means on said body and said abrasive elements for guiding said abrasive elements longitudinally and for moving the abrasive elements radially of the body upon longitudinal movement, actuating elements mounted in the hone for longitudinal sliding movement therein and engageable with said abrasive units effective for moving the units longitudinally in one direction, a pair of thrust members mounted in said shank for longitudinal sliding movement therein, one thrust member being engageable with said actuating members and the other extending to adjacent the end of the shank opposite the body for engagement by operating means, and pre-loaded spring means operatively interposed between said thrust members.

20. A rotatable hone comprising a tubular drive shank, a generally cylindrical body mounted on the shank, a plurality of abrasive elements movably carried by said body, mutually interengageable means on said body and said abrasive elements for guiding said abrasive elements longitudinally and for moving the abrasive elements radially of the body upon longitudinal movement, actuating elements mounted in the hone for longitudinal sliding movement therein and engageable with said abrasive units eective for moving the units longitudinally in one direction and resiliently urging the units radially inwardly, a pair of thrust members mounted in said shank for longitudinal sliding movement therein, one thrust member being engageable with said actuating members and the other extending to adjacent the end of the shank opposite the body for engagement by operating means, and pre-loaded spring means operatively interposed between said thrust members.

21. An abrasive unit for a hone comprising an elongate carrier body having an upper surface and laterally spaced side surfaces, longitudinally spaced cam lugs on each of said side surfaces and extending laterally outwardly therefrom and having inclined surface portions on their undersides, and an abrasive element secured to said upper surface of said carrier body, said abrasive element being shorter than said carrier body and the carrier body thereby having end portions extending longitudinally beyond the ends of the abrasive element, said end portions having transverse grooves in said upper surface.

22. An abrasive unit for a hone comprising an elongate carrier body having an upper surface, laterally spaced side surfaces and a bottom surface, longitudinally spaced cam lugs on each of said side surfaces and extending laterally outwardly therefrom and having inclined surface portions on their undersides, a retaining lug extending from said bottom surface and having an enlarged head portion adjacent its extended end, and an abrasive stone secured to said upper surface of said carrier body.

23. A rotatable hone comprising a tubular drive shank, a head having a body and a stem disposed in and secured to said shank, said body and stem being formed with a plurality of slots opening into said shank, a plurality of abrasive units carried on said body, means on said body guiding said units for simultaneous longitudinal and radial sliding movement thereon, means for resiliently opposing outward radial movement of said units on said body, and actuating means for moving said units longitudinally including a plurality of elongate elements slidably disposed in said slots within said shank and extending from said shank and having outer end edges abutting inner end edges of said units respectively, and means in said shank for resiliently urging said elongate elements in a direction inwardly of said shank.

24. A rotatable hone comprising a tubular drive shank, a head having a body and a stem disposed in and secured to said shank, and formed with a plurality of slots opening into saidshank, a plurality of abrasive units carried on said body, means on said body guiding said units for simultaneous longitudinal and radial sliding movement thereon, means for resiliently opposing outward radial movement of said units on said body, and actuating means for moving said units longitudinally including a plurality of elongate elements slidably disposed in said slots within said shank and extending from said shank and having their outer ends engaging said units respectively solely by abutment with the inner end edges thereof, and means in said shank for resiliently urging said elongate elements in a direction inwardly of said shank.

25. A rotatable hone comprising a tubular drive shank, a head having a body portion and a stem disposed in and secured to said shank, said body and stem being formed with a plurality of slots opening into said shank, a plurality of abrasive units carried on said body, means on said body guiding said units for simultaneous longitudinal and radial sliding movement thereon, means including synthetic rubber rings encircling said units for resiliently opposing outward radial movement thereof on said body, and actuating means for moving said units longitudinally including a plurality of elongate elements slidably disposed in said slots within said shank and extending from said shank and having their outer ends abutting inner end edges of said units, and means in said shank for resiliently urging said elongate elements in a direction inwardly of said shank.

References Cited in the file of this patent UNITED STATES PATENTS 149,494 Margedant Apr. 7, 1874 773,223 Power Oct. 25, 1904 1,408,706 Long Mar. 7, 1922 2,001,122 Brickner May 14, 1935 2,269,378 Palotce Jan. 6, 1942 2,316,879 Mattson Apr. 20, 1943 2,376,851 Sunnen May 22, 1945 2,379,210 Alyea .Tune 26, 1945 2,419,136 Hasty Apr. 15, 1947 2,419,660 Satterthwaite Apr. 29, 1947 2,453,717 Long Nov. 16, 1948 2,483,997 Gjertsen Oct. 4, 1949 2,663,124 Smole Dec. 22, 1953 FOREIGN PATENTS 106,549 Australia Feb. 1, 1939 

